Sherwin PSM5 TAM Panel (Grit)

Details

Sherwin PSM-5 Penetrant System Monitor Panel:

A chrome plated strip approximately 44.5 mm wide x 0.076 mm thick (1.75 x 0.003 in.) covers the length of the panel and the remaining area is a grit blasted surface of medium roughness used for determining penetrant material's washability. The chrome plated strip contains five cracked centers evenly spaced at 25 mm (1 in.) apart. These cracked centers are in circular patterns and vary in size from about 3.8 to 6.3 mm (0.015-0.25 in.) in diameter and are arranged in order of magnitude. The cracks may disseminate from the center in a star burst or a linear pattern.

Panel manufacturers also provide Tam panels for which the chrome strip has been lightly grit blasted. These types of Tam panels are recommended when parts or components with rough surfaces are to be liquid penetrant inspected.

Although neither MIL-STD-6866 nor ASTM E 1417 specify the type of known defect standards to be used for the system performance check, several aerospace specifications require the use of Tam panels for this function. These specifications require that penetrant inspection materials exhibit a specified number of indications based on their respective sensitivity level

Sherwin Incorporated is an authorized manufacturer of TAM 146040 panels.

There are a number of good reasons to read and understand the instructions. For example, a TAM panel is to be dedicated to a single penetrant line, and that line is to have only one kind of penetrant in it. A new panel is processed through the line, and the number of indications is recorded. This calibrates the panel, and establishes the number of indications which should be expected each time that particular panel is processed through the same penetrant line. If the panel initially shows three indications, and one day it only shows two indications, it is a sign that there might be a problem in the line, either with the materials, with the processing parameters, or the test panel itself.

ALL PANELS ARE NOT EQUAL

Suppose that you have a panel which shows three indications on a certain penetrant line. If you buy another panel and process it through the same line," how many indications should you expect to find?" Many would say “three”, but that is not necessarily true. It could be two, or three, or four, or even five. No two panels are the same. This is the reason why a single panel must be dedicated to a single penetrant line, and calibrated to that line. Suppose that you are using a panel which always shows four indications, and you decide to also use a second panel which shows three indications. The penetrant line is performing properly if the first panel shows four indications and the second shows three. The manufacturing drawing calls for the star burst indications to be within a specified size range . A 0.015-0.031" (0.38-0.79mm) B 0.046-0.062" (1.17-1.57mm) C 0.075-0.093" (1.91-2.36mm) D 0.125-0.171" (3.18-4.30mm) E 0.180-0.250" (4.57-6.35mm)

This means it is possible to have a panel with all high end or low end limit indications which would give different results through the same system. A panel with high end C, D, & E indications and low end A & B would also yield different results than one with star bursts of the reverse relationship. This and other reasons are why the panels are not sensitivity panels and this is clearly stated in the instructions from each of the manufacturers and by the originators, Pratt & Whitney. It is a process monitoring device which is to be dedicated to one process line to monitor consistency of the process. This fact has been overlooked by even seemingly knowledgeable NDT engineers, auditors,and level 3's who think they can assign a value of sensitivity by the number of stars that appear on a panel. They are mistaken!

We cannot exchange new panels that do not meet a customers expected dedicated sensitivity level as these TAM panels are not designed for this purpose